1. Field of the Invention
The present invention relates to electrical connectors and more particularly, to an improved structure of electrical connector, which has grounding spring plates mounted in recessed locating portions at two opposite sides of the electrically insulative housing and bonded to the circuit board that is mounted in a rear accommodation space in the rear side of the electrically insulative housing for grounding to avoid electromagnetic wave interference.
2. Description of the Related Art
Following fast development of computer technology, versatile desktop computers as well as notebook computers have been continuously created. These advanced computers have the characteristics of strong computing function, fast operating speed, small size and high transmission speed. The most popularly used USA connectors include two types, i.e., the type of transmission speed at 1.5 Mbps and the type of transmission speed at 12 Mbps. These two transmission speeds are faster than the parallel ports or serial ports that are currently used in computers. Therefore, the use of USB connectors in a computer greatly improves the transmission efficiency between the computer and the related peripheral equipments such as keyboard, mouse, modem, joystick, scanner and etc.
To fit the developing tendency of computer toward a small-sized design, electrical connectors for computer must be relatively small-sized. However, the problem of electromagnetic interference must be taken into account when designing a small-sized electrical connector for computer. Signal interference of an electrical connector may come from external electromagnetic waves or the inside noises. During operation of an electrical connector, external electromagnetic waves from an external transmission line may interfere with the transmission of power supply or signal in the electrical connector, and this interference may affect the surrounding electronic components or circuits, causing a signal transmission error or failure or affecting the signal transmission quality of the electrical connector.
Therefore, filter means is usually used for suppressing electromagnetic interference, maintaining signal integrity. A filter device for this purpose is usually installed in a circuit board inside the host. However, the installation of a filter device in a circuit board is complicated and requirements much installation space. Some suppliers have the electrically insulative housing of each the provided electrical connector be surrounded with a metal shield, which has spring strips for contacting or bonding to the circuit board in the electrically insulative housing for connecting to external metal object for grounding. The spring strips may be formed of a part of the metal shield through a stamping technique. This spring strip formation procedure complicates the fabrication of the metal shield and wastes much the metal material. A filter module and/or grounding terminals may be installed in the circuit board inside the electrically insulative housing of an electrical connector to eliminate the interference of noises. However, the arrangement of filter module and/or grounding terminals complicates the circuit layout of the electrical connector. Further, arranging multiple grounding terminals and signal terminals in the limited surface area of a circuit board for electrical connector may cause electromagnetic interference among the terminals, lowering signal transmission stability and the shielding effect of the metal shield.